Water heating system



1941- c. M. OSTERHELD 2,266,250

- WATER HEATING SYSTEM Filed Nov. 16, 1940 INVENTOR CLARK- USTERHELD BYMm AT T ORNEY Patented Dec. 16, 1941 WATER nm'rmc SYSTEM Clark M.Osterheld, Stoughton, Wis., assignor to McGraw Electric Company, Elgin,111., a corporation of Delaware Application November 16,1940, Serial No.365,920

3 Claims.

My invention relates to electric water heating systems and particularlyto continuously operative systems for such purpose.

An object of my invention is to provide a relatively simple systemcomprising a minimum number of control elements efiective to maintain ina heated condition a part of the water content of a tank during one partof a day and to heat substantially all of the water in the tank duringanother part oi. the day.

Another object of my invention is to provide a water heating systemefiective to maintainv different amounts of water in a tank in a heatedcondition during different partsof a day, controllable by remotelylocated relatively simple means.

Other objects of my invention will either be apparent from a descriptionof several modifications embodying my invention or will be pointed outhereinafter in the course of such description and will be set forth inthe appended claims.

In the drawing,

Figure 1 is a diagrammatic representation of my improved water heatingsystem as applied to an ordinary domestic hot water tank, and,

Fig. 2 is a view similar to Fig. 1 but showing a modified systemembodying my invention.

Referring first to Fig. 1 of the drawing, I have there illustrated anordinary hot water tank ll illustrated as being of elongated cylindricalshape, such as used in ordinary household installations. The tank may besurrounded by a mass l3 of heat insulating material which may be held inplace and protected by an outer casing IS.

The tank is provided with a cold water inlet pipe I! connected therewithat the bottom and with a hot water outlet pipe l9 connected therewith atthe top of the tank. It is to be understood that while I am illustratingparticular details of construction of a tank and its covering, I do notdesire to be limited thereto since any equivalent structure now known inthe art may be used by me.

I provide a single electric heater 2| which may be of the kind disclosedand claimed by me in my Patent 'No. 2,226,526 issued December 24, 1940.Since the heater itself forms no part of my present invention, it isillustrated generally only but I may point out that I prefer to locatethe heater near the bottom end portion of the tank.

I provide further a main thermally actuable switch 23 here shown as asimple bimetallic element which is subject to the temperature of thewater in the tank near the bottom end portion of the tank. The positionsof the heater and of the mainthermostaticswitch 23 controlling theheater are such that the contacts of switch 23 will be in engagementwitheach other as long as the thermal switch is subject to cold water,

but that the contacts will be disengaged from each other whensubstantially all of the water in the tank is hot.

I provide further an auxiliary thermal heater control switch 25 hereshown generally only as including a flexible bimetallic element of thekind now well known in the art. This auxiliary thermal heater controlswitch is adapted to be mounted at a convenient or desired point alongthe height of the tank and it is, of course, obvious that the amount ofwater which must be hot in order to cause opening of any circuitcontrolled by the thermal switch 25 will vary in accordance with and beproportional to the position of this auxiliary thermal switch. Theamount of water which corresponds to the auxiliary switch 25 iscomprehended in the phrase used hereinafter that a predeterminedfractional part of the water content of the tank is hot or is cold.

ated by either its own bias or by a suitable biasing means, intoengagement with the contact 29.

The switching means includes further a stationary electromagnetic coil35 and a magnetizable core member 31 fixed therein which latter isadapted to energize a suitable armature '39 mounted on the contact arm 3I, to thereby counteract or overcome the bias of contact arm 3| abovedescribed and cause movement of the contact arm in a direction to causeit to engage fixed contact member 33.

A' pair of supply circuit conductors 4| and 43 are provided and it is tobe understood that these conductors are energized continuously. Supplycircuit conductor 4! is connected by a conductor 45 to contact arm 3!.Contact arm 21 or its equivalent contact 29 are connected by a conductor41 to the fixed contact of the upper thermal switch 25. The otherterminal of switch 25 is connected by a conductor 49 to one terminal ofheater 2i, the other terminal of which is connected by a conductor 5|tothe other supply circuit conductor 43. Contact member 33 is connectedby a conductor 53 to one of the terminals of the main thermal switch 23,the other termiordinary standard frequency type. I have illusas beingelectrically connected with the other supply circuit conductor 43.

It is to be understood that the operationof the generator 57, or of itsequivalent, is continuous so that supply circuit conductors 4i and 43will be 53 as by conductors l3 and 15 between terminals oi. the switchI! and the conductors 6| and 63.

energized at all times. Under these conditions as to energization of thesupply circuit, current flow will be established through the heater 2|and through the auxiliary heater control switch 25 as long as the amountof hot water in the tank is less than sufiicient to affect and open theauxiliary thermal switch 25. The path of this current is as follows:From conductor 4| through conductor 45 to and through theengaged contactarms 3| and 27, through conductor 41 to and through the auxiliary switch25 (which will be in The terminals of coil 35 are connected by suitableconductors to the supply circuit conductors 4| and 83.

The switch 7| will be maintained in open position during all of theon-peak period but when the operator desires to eiiect energization ofheater 2| through another circuit including the main thermal heatercontrol switch 23, it is only necessary that the switch ll be closed tothereby energize the coil 35 by the high frequency current, whichenergization will result in causing contact arm 3| to move intoengagement with contact member 33 whereby the following heaterenergizingcircuit is closed: From conductor 4| through conductor 55 to the contactarm 3|, to contact 33, through conductor 53 to and through the mainthermal switch 23 and from there through the heater 2| and conductor 5|to q the other supply circuit conductor 43. As long closed position),through conductor 49 and from there through heater 2| and conductor 5|to the other supply circuit conductor 43. In ordinary domesticinstallations, withdrawals of hot water occur at odd times during theday, as hot water is needed, and as long as the amount of hot water inthe tank is less than suflicient to afiect the auxiliary thermal switch25, this current flow will continue. However, if the effect of theheater 2| when so energized is to increase the amount of hot water inthetank to such an extent that the auxiliary heater control switch 25will open, energization of the heater 2| will be terminated until suchtime as suflicient hot water is withdrawn to cause the auxiliary switch25 to be responsive to cold water and to be moved to closed position.

- tion.

as switch H is closed this second heater control circuit will beefiective and this heater circuit is controlled electrically by theremotely 10- cated control switch H and thermally by the main thermalheater control switch 23. As was hereinbefore stated,'this main thermalheater,

control switch 23 is efiective to disengage its contacts whensubstantially all of the water in the tank is. hot and it is,therefore,- evident that should all of the water in the tank be hot be-7 contact member 29 whereupon the primary heater control circuitincluding the auxiliary thermal switch 25 will tend to maintain in aheated condition a predetermined fractional part of the water content ofthe tank during a predetermined part (the on-peak part) of a twenty-fourhour Most central stations provide for an oil-peak period, usuallyextending during the greater part of the night, and for illustrativepurposes we may consider an off-peak period to start at 10:00

p. m. and to extend for eight hours thereafter,

desired kind to provide the desired high frequency alternating currentand its circuit may include an adjustable condenser 61 and an adjustablereactor coil 69 in order that proper tuning may be effected. between theremotely positioned. control station and the coil 35 on the customer'spremises. I provide a control switch ll in the central station which forconvenience is indicated as being manually actuable. The

switch 1| permits of connectingthe high ire quency current to theconductors 8| and 63 and day.

While I have illustrated and described a specific' embodiment of aremotely located and remotely energizable control means for thetwooperative-position switch, it is obvious that I may use any othersuitable control means which, for

instance, may include a separate set of circuit conductors controllableby any suitable means. which means is locatedin the central station.

Referring now to Fig. 2 of the drawing, I have i there illustrated asomewhat modified form of system embodying my invention which permitstherefore to the supply circuit conductors 4| andi 5 of deenergizing theheater control system entirely should it be considered desirable, by theengineers in the central station, to do so. Thus it might happen thatfor reasons unexpected and beyond control, a heavy load is applied tothe central station and it isdesired to eflect-disconnection of all ofthe water heater systems normally connected to'the supply ordistribution 2,260,250 tact arms 19 out of engagement with contact 11,

I provide a relay coil 85 having a core member 81 fixed therein whichcore member is adapted when magnetized by energization of the coil 85,

i to magnetize an armature I! on contact arm 19 and cause the arm I9 tobe moved out of engagement with contact member 11. Contact am I9 isconnected by a conductor 9| to supply circuit conductor ll.

The central station 55 includes, in this case, not only the alternatingcurrent generator 51 of standard frequency and a first high frequencygenerator 65, but also a higher frequency generator 93, both of whichmay be driven by any suitable or desired means. The first high frequencygenerator 65 is controlled as to its supply of energy to the system bythe switch H while a switch 95 is adapted to control the second orhigher frequency generator above described. It is to be understood thatboth terminals of the high frequency generators are suitably connectedto the conductors SI and it.

In Fig. 2 of the drawing I have shown an ad- J'ustable condenser 9'! andan adjustable reactor 99 as associated with the two-operative-positionswitch and have shown an adjustable condenser Ill and an adjustablereactor I03 as associated with the single-operative-position switchwhich ,is effective to interrupt the energization of the water heatingsystem shown in this and in the other figure of the drawing.

The operator at the central station may move 'the switch 1! for the highfrequency generator as was described above in connection with Fig. 1 ofthe drawing to cause the heater 2| to be energized during the daywhenever required to maintain in a heated condition a predeterminedfractional part of the water content of the tank to counteract or takecare of the withdrawals of hot water therefrom during the greater partof the day. When switch II is closed energization of coil 35 will occurand cause movement of contact arm 3| whereby the main thermal switch 23will be put into the heater energizing circuit with the result that thesystem will then tend to maintain in a heated condition substantiallyall of the water content of the tank and this may be done during theofl-peak period of a twenty-four hour day.

Should an extreme overload occur on the central station, the operatorwill close switch 95 of the higher frequency generator which iseifective to energize coil 85 of the single-operative-position switchwhich will result in interrupting the flow of 'current, if present atthat time, through the heater 2|.

It is to be noted that my system includes a relatively small number ofcontrol elements,

particularly switches, and that these switches may be controlled as tothe energization of the heater 2| by remotely located means of a verysimple kind to obtain the desired result. It may, be noted that noadditional control circuits between the control station and. therespective customers installations are required, the usual alreadyinstalled power lines being sumcient. My system provides at least acertain amount of hot water in the tank, less than the total amount inthe tank, during say the daylight hours and the Various othermodifications may be made in the system embodying my invention withoutdeparting from the spirit and scope thereof and all other modificationsclearly coming within the scope of the appended claims are to beconsidered as being covered thereby.

I claim as my invention:

1. An electric water heating system for a hot water tank having a singleelectric heater at the lower end of the tank, comprising a main and anauxiliary thermal heater control switch responsive to tank watertemperature at difierent heights of the tank, a two operative-opositionheater control switch normally yieldingly biased into a first positionto cause energization of the heater through said auxiliary thermalswitch in case less than a predetermined fractional part of the watercontent of the tank is hot, and manually-actuable remotely controlledelectromagnetic means to cause said two-operativeposition switch to moveinto and be held in its second position to cause energization of theheater through said main thermal switch only in case less thansubstantially all of the water in the tank is hot.

2. A water heating system for a hot water tank having a single electricheater adjacent to the lower end of the tank, comprising a pair ofthermal heater control switches at different heights of the tank, atwo-operative position heater control switch normally yieldingly biasedinto one of its operative positions to cause energi'zation of the heaterthrough the upper of said thermal switches in case said upper thermalswitch is subject to cold water, electromagnetic means for causing saidtwo-operative position heater control switch to move into its otheroperative position to cause energization of the heater through the lowerof said thermal switches in case said lower thermal switch is subject tocold water, a heater control switch in series circuit with saidtwo-operative position switch normally yieldingly biased into circuitclosing position, and electromagneticmeans to cause opening movement ofsaid last named heater control switch to deenergize the heating system.

3. A water heating system for a hot water tank having a single electricheater adjacent to the lower end of the tank, comprising a pair ofthermal heater control switches at diflerent heights of the tank, atwo-operative position heater control switch normally yieldingly biasedinto one of its operative positions to cause energization of the heaterthrough the upper of said thermal switches in case said upper thermalswitch is subject to cold water, electromagnetic means for causing saidtwo-operative position heater control switch to move into its otheroperative position to cause energization of the heater through the lowerof said thermal switches in case said lower thermal switch is subject tocold water, a heater control switch in series circuit with saidtwo-operative position switch normally yieldingly biased into circuitclosing position, electromagnetic means to cause opening movement ofsaid last named heater control switch to deenergize the heating systemand remotely located means for selectively energizing said plurality ofelectromagneticnieans at the will of an operator.

CLARK M OSTERHELD.

